A solid-oxide fuel cell (SOFC) typically includes a unit cell as a basic structural element which comprises an electrolyte layer such as yttria-stabilized zirconia and an anode (fuel electrode) and a cathode (air electrode) attached to both sides of the electrolyte layer. It is typical that the electrolyte layer such as yttria-stabilized zirconia has a dense structure so as not to allow fuel to be mixed with air whereas an anode and a cathode has a porous structure so as to allow fuel and hydrogen to be efficiently diffused.
The solid-oxide fuel cell has been developed into a planar fuel cell and a tubular fuel cell. Furthermore, the tubular fuel cell may be classified into a cylindrical fuel cell and a flat-tubular fuel cell which is flattened to allow the fuel cells to be easily stacked. A method which is usually used in the production of the planar fuel cell and the tubular fuel cell is embodied by reducing resistance of a fuel cell by applying a thin electrolyte film on an electrode support in order to improve an output density of a unit cell for solid-oxide fuel cell.
In the planar solid-oxide fuel cell, although the layering of cells and the collection of current are facilitated because a metal connecting plate is used, there are disadvantages in that it is difficult to manufacture a large-area planar cell and an additional seal material is required to separate flows of fuel and air at upper and lower parts of the cell.
For the planar solid-oxide fuel cell, a metal connector, which is currently used as a connecting plate functioning to isolate fuel from air and to connect fuel cells in a series circuit manner, has shown the general problems of corrosion at a high temperature and deterioration of performance of the fuel cell owing to reaction of a cathode of a solid-oxide fuel cell and Cr volatilized from a stainless alloy. The problems of the connector have a critical effect on the durability of a solid-oxide fuel cell stack.
A conventional solid-oxide fuel cell is configured to separate flows of fuel and air using a metal connector and a cell frame and supply the separated fuel and air to a front part and a rear part of the cell. The conventional solid-oxide fuel cell has problems such as difficulty in forming a seal between the cell and the metal plate, an increase in the weight of the stack and the load to the cell, an increase in volume of the stack and increases in manufacturing costs of the stack due to metal working costs.
Conventional technologies relating to the field of the present invention may include Korean Pat. Nos. 10-0538555 and 2008-0131314.